#126 Preparation and evaluation of Diltiazem hydrochloride transdermal patches using film casting technique

The present investigation develops controlled release matrix type transdermal patches of diltiazem hydrochloride using natural and biodegradable polymer hydroxyl propyl methylcellulose. Any type of formulation that allows a drug substance to transit from outside of the skin through the layers of skin to underlying tissues and finally into the systemic circulation to exert a pharmacological action is called a transdermal drug delivery system. Dose of diltiazem hydrochloride 180-240 mg daily, melting point 210-215 °C, and overall drug lipophilicity make the drug suitable for transdermal drug delivery system. Transdermal patches were prepared by film casting technique. 73.96 g of Diltiazem hydrochloride and HPMC in the ratio of 3%, 4%, and 5% were dissolved in ethanol and chloroform (1:1 mixture) and castor oil 30% w/w of polymer used as a plasticizer. The mixture was poured into a glass plate using a ring of 4.3 cm diameter having 5 mL capacity. After drying at room temperature for 24 h, circular film of 1 cm diameter (area of 0.785 cm²) each containing 4 mg drug was cut. The prepared formulations were evaluated for their physical characteristics such as percentage moisture absorption, thickness, weight, and drug content. The physico-chemical evaluation data revealed that percentage moisture absorption is high in formulation F6 and low in formulation F2. Thickness and weight uniformity were in the range of 0.036±0.004 to 0.040±0.006mm and 0.024±0.005 to 0.045±0.003 mg, respectively. The drug content was found to be 90.3±0.050% to 93.1±0.071% in the prepared delivery system. In vitro drug release revealed that the formulation F1, F2, F3, F4, F5, and F6 releases 77.05%, 73.22%, 68.59%, 67.07%, 59%, 48.41% of the loaded drug at the end of 24 h from the formulations, respectively. The formulation F5 containing 4% HPMC as drug reservoir of diltiazem hydrochloride and EC 5% as rate-controlling membrane has shown best release at the end of 24 h in a concentration-independent manner. In conclusion, formulation F5 achieved the targets of the present study, such as: Reducing the frequency of administration and no systemic side effects. Hence it may improve patient compliance.